This unique tool was designed to make sizes 35 thru 240 chain installation easy. By hooking the two jaws into each end of the chain and turning the screw (handle) until the two ends almost meet, the connecting link can be inserted and fastened in place. The model 80 uses a T-handle instead of a knob. Dodge® Chain Assembly Tool, For Use With: 80 to 240 Numbers Chain, 5 in Maximum Jaw Spread